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    <h4>计算可以通过多少次路口:</h4>
    <script>
      // 计算可以通过多少次路口:"
      function cross(money) {
        var tmp = 0;
        while (money >= 5000) {
          if (money >= 50000) {
            money = parseInt(money * 0.95);
            tmp += 1;
          } else if (money < 50000 && money >= 5000) {
            money -= 5000;
            tmp += 1;
          }
          // document.write(money + " ");
        }
        document.write(tmp + "次");
        document.write("<br>");
      }
      var money = prompt("输入数字");
      cross(money);

      // document.write("3.求出1-1/2+1/3-1/4…..1/100的和:");
      // var res = 1;
      // for (var i = 2; i <= 100; i++) {
      //   i % 2 == 0 ? (res -= 1 / i) : (res = res + 1 / i);
      // }
      // document.write(res);
    </script>
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